[part9]Remove singleclient outdated api

[luqiang-guo]

删除multiclient 下single client的接口
总删除列表

此pr完成了一部分接口清理。

• load_variables
• current_machine_id
• current_resource
• current_global_function_desc
• ExecutionConfig
• global_function

[chengtbf]

这些是不是也一并删掉？

[clackhan]

一并删除

[clackhan]

上面对应的这两个函数也一并删除

[chengtbf]

这个文件的改动请 @daquexian 大老师看一下吧~

[daquexian]

对这个函数的调用也一起删掉吧，应该在 session_util.py

[github-actions]

Speed stats:

GPU Name: GeForce GTX 1080 

PyTorch resnet50 time: 140.2ms (= 7011.7ms / 50, input_shape=[16, 3, 224, 224], backward is enabled)
OneFlow resnet50 time: 128.2ms (= 6409.8ms / 50, input_shape=[16, 3, 224, 224], backward is enabled)
Relative speed: 1.09 (= 140.2ms / 128.2ms)

PyTorch resnet50 time: 84.9ms (= 4244.5ms / 50, input_shape=[8, 3, 224, 224], backward is enabled)
OneFlow resnet50 time: 74.5ms (= 3726.0ms / 50, input_shape=[8, 3, 224, 224], backward is enabled)
Relative speed: 1.14 (= 84.9ms / 74.5ms)

PyTorch resnet50 time: 58.6ms (= 2931.0ms / 50, input_shape=[4, 3, 224, 224], backward is enabled)
OneFlow resnet50 time: 50.1ms (= 2504.1ms / 50, input_shape=[4, 3, 224, 224], backward is enabled)
Relative speed: 1.17 (= 58.6ms / 50.1ms)

PyTorch resnet50 time: 45.9ms (= 2296.4ms / 50, input_shape=[2, 3, 224, 224], backward is enabled)
OneFlow resnet50 time: 41.5ms (= 2072.6ms / 50, input_shape=[2, 3, 224, 224], backward is enabled)
Relative speed: 1.11 (= 45.9ms / 41.5ms)

PyTorch resnet50 time: 43.7ms (= 2184.0ms / 50, input_shape=[1, 3, 224, 224], backward is enabled)
OneFlow resnet50 time: 45.3ms (= 2267.3ms / 50, input_shape=[1, 3, 224, 224], backward is enabled)
Relative speed: 0.96 (= 43.7ms / 45.3ms)